Raw milk is stored on dairy farms in milk holding tanks, or bulk tanks, until the milk is collected by a milk transport company and transported by truck to a dairy plant or the like. According to current practice, the transport trucks are equipped with a positive-displacement pump, which when coupled to the bulk tank, serves to transfer a quantity of milk from the bulk tank to the transport truck reservoir tank. The trucks are equipped with an appropriate sanitary hose having one end connected to the inlet of the positive-displacement pump, with the other end of the hose adapted to be coupled to the outlet of the bulk tank. According to the current set-up, the positive-displacement pump typically transfers milk from the bulk tank at an average rate of about 350 litres per minute. Once the appropriate quantity of milk has been transferred from the bulk tank, or the bulk tank has been emptied, the driver disconnects the hose and starts the bulk tank washer before leaving. The entire process usually takes about 35 minutes.
Due to changes in the dairy farming industry, the number of farms producing milk has been decreasing. However, the remaining farms are larger in size and produce a greater volume of milk. This trend is expected to continue with the number of farms further decreasing while the volume of milk produced by each farm increases. Therefore, the efficiency with which the driver or operator of the transport vehicle can transfer milk from the bulk storage tanks to the vehicle tank and begin the necessary sanitizing operations will become more important as the amount of milk stored on each farm increases.
U.S. Pat. No. 5,878,767 to Etling et al. discloses a system for transferring fluid from a filling reservoir to a receiving tank that substantially eliminates the escape of any residual fluid or any undesirable odours (if the fluid is odorous) from the fluid transfer lines when they are uncoupled from the tanks. The system includes a portable platform with a centrifugal pump mounted thereon which, when operated, induces fluid to travel from the filling reservoir to the receiving tank through the transfer lines. The system also includes a compressed gas source in communication with the fluid transfer line for blowing gas through the line to remove any residual fluid from the line, and provides for a vapour return line interconnecting the filling reservoir inlet and the receiving tank vent. The disclosed system mainly relates to the transfer of odorous chemicals, wherein the escape of any fluid or odour to the environment is undesirable. As well, the pump is used solely for selectively transferring fluid from one tank to another and is not adaptable for use in cleaning or sanitizing operations which are required when dealing with consumable products such as milk.